Abstract

Converting CO<inf>2</inf> into formic acid through hydrogenation is vital for reducing greenhouse gas emissions and producing valuable chemicals. Due to the high cost and scarcity of platinum, efficient platinum-based catalysts are essential. This study uses density functional theory (DFT) calculations to investigate CO<inf>2</inf> hydrogenation on defective carbon nanocones (dCNC) decorated with Pt<inf>4</inf> clusters (Pt<inf>4</inf>/dCNC) and examines the effect of nitrogen doping (Pt<inf>4</inf>/N<inf>x</inf>dCNC, where x = 1, 2, 3). Two reaction pathways were evaluated: co-adsorption and a combination of H-spillover with co-adsorption. The latter, via a formate intermediate, was identified as the most favorable. Nitrogen doping, particularly in Pt<inf>4</inf>/N<inf>3</inf>dCNC, significantly enhanced catalytic activity compared to non-doped Pt<inf>4</inf>/dCNC. This improvement is attributed to increased active sites from nitrogen doping. The H-spillover process to nitrogen in N<inf>3</inf>/dCNC lowered the energy barrier to 0.43 eV, with the final hydrogenation step nearly barrierless. Strong linear correlations were found between overall free energy barriers (ΔG<inf>overall</inf>^#), rate-determining step barriers (ΔG<inf>RDS</inf>^#), and the free energy differences of key intermediates, highlighting the critical role of nitrogen doping in enhancing catalytic performance and providing valuable insights for catalyst design.